1. Field of the Invention
The present invention relates to a method for forming a semiconductor device with a double-layer spacer. Owing to the double-layer spacer, the width of the spacers of the interior circuit and the peripheral circuit can be controlled to provide semiconductor devices of high quality.
2. Description of the Prior Art
Recently, the demand for semiconductor devices has rapidly increased owing to the widespread use of integrated electronic circuit. In particular, as an excess of than hundreds or thousands of electrical components are integrated into ICs, the need for higher quality semiconductor devices and more simplified fabrication has become imperative.
FIG. 1 shows a cross-sectional view of a traditional semiconductor device. For example, the gate substrate is usually composed of polysilicon 140A and 140B, tungsten silicide (SiW) 160A and 160B, and silicon oxide 180A and 180B. However, the gate substrate needs two steps to form a bit-line to substrate 340A and 340C contact via and a bit-line to gate contact via 340B. Further, spacers 220C and 220D are composed of silicon nitride of a traditional semiconductor device due to the structure substantially not controlling the thickness of the spacers of interior circuit and the peripheral circuit.
For the foregoing reasons, there is a need for a method of forming higher quality semiconductor devices and more simplified fabrication.